Electric lamp



Nov. 8, 1938. G. E. INMAN 2,135,714

`ELECTRIC LAMP Filed Aug. 10, 1934 3 Sheets-Sheet l Inventor: GeorgeElnm r1, y @lis-'At torney.

GA E. INMAN 2,135,714

Nov. 8, 1938.

ELECTRIC LAMP Filed Aug. 10, 1934 5 Sheets-Sheet 2 Inventor: GeorgeInman H i) by Hwttohey.

G. E. :NMAN 2,135,714

ELECTRIC LAMP Filed Aug. 1o, 1%1 5 sheetssheet 5 FTQ. H.

Inventor: George E. Inman,

vim

Patented Nov.. 8, 1938 ELECTRIC LAMP George E. Inman,

New York East Cleveland, Ohio, assigner to General Electric Company,

a corporation of Application August 1c, 1934, serian N. 739,271'

15 claims. (ci. 17o- 1) This invention relates to electric lamps and thelike, and especially to glow discharge vapor lamps such as the so-calledlow pressure positive column type or the cathodic glow type, givingdiffuse rather than sharply localized or intense concentratedluminosity. The invention is concerned with lamps that contain avaporizable vworking substance,e. g., sodium and some other metals-andoperate with very small vapor prassures of such substance. In suchlamps, the absolute vapor pressure of the working substance is usuallyabout 1 or 2 microns for sodium. Vapor pressures of low order arecharacteristic of the typical diffuse glow discharge, that generallyappear toflll the whole lamp bulb. Very usually, such lamps contain asmall amount of easily ionized gas, like neon, argon, etc., whose(partial) pressure in the lamp is around 1 or 2 to 7mm., to assist instarting the sodium or other vapor discharge. lThis is the moredesirable in lamps using a difiicultly vaporizable working substancelike sodiumas contrasted with one that is more easily vaporized likemercury. Commercial sodium vapor lamps aim at operating temperaturesaround 250v C. for maximum efficiency; while the actual temperatures oftheir envelope or bulb walls range from about 220 C.

vis made to remedy this by v heated by its glow discharge;

or less to about 275 C. or more. The boiling point of sodiumbeing about877 C., the sodium vapor in the commercial lamp bulb is continuallycondensing on itsinner surface and vaporizing again, with a tendency toaccumulate and remain in any region or area that is relatively cool,because of the l,slower vaporization from the cooler region. This meansthatvthe sodium vapor pressure in the envelope will tend to fall belowthat corresponding to the general lamp temperature, and to approach thatcorrespondingto the lowest temperature: i. e., thatthe lamp willvirtually lack sodium, and its light outputY and cihciency'suiercorrespondingly. Or if the attempt forcing the lamp to operate at ahigher current density in the glow discharge, and thus heat up itscoolest region(s) to 250 C. or thereabout, then the general lamptemperature will be forced still higher, and the eiciency will alsosuier.

' Practically, it is very dimcult to designa commercial lamp of the glowdischarge type containso as to be evenly and the variation in walltemperature is apt to be even less favoring diiculty vaporizing metal4able than the above-suggested range of I220" C. to

275 C. in the sodium vapor lamp.

While an adequate though small vapor pressure of sodium or the like isessential to the operation of a glow discharge vapor lamp, and while themost favorable sodium pressure for efliciency is that corresponding to a(uniform) temperature of about 250 C., the current density in the glow 6discharge is also very important to the ecency,

and in a contrary sense: i. re.,'the lower the current density, thegreater the luminous efliciency of the glow discharge. However, glowdischarge currents that would be highly favorable from this 10 point ofview are insufiicient to heat the lamp to the temperature that is mostfavorable as regards vapor pressure of a working substance such assodium. This is so even when the sodium vapor lamp is operated in adouble-walled vacuum jack. 15 et in order to conserve heat, as iscustomary.

Other limitations and drawbacks of such vapor lamps have lain in thenecessity of a ballast re sistance in series with the lamp, to controland limit rise of current through the lamp as it heats up; and of eitherproviding compensating resistances, reactors, or transformers to allowsuch lamps to operate in parallel on ordinary (alternating current)lighting circuits of `1l0- 120 volts-or else operating a. lurality ofthe lamps in series.

I have found that these difficulties can be overcome, and a very highoperating efficiency realized in a lamp of this general type, bysupplying additional heat, as uniformly as possible or as nearlyaccording to the deficiency inthe various parts of the lamp as possible,so as to maintain a proper uniform lamp temperature with a relativelylow glow discharge current, or current density. Preferably, andashereinafter described, 35 the lamp is heated externally. Suitableelectrical heating means for this purpose may be operated independently,from a separate heating circuit, or may be adapted and used to ballastthe lamp, or may be used to compensate for its low operating voltage.Useful light may be obtained from an incandescent b'ody aswell as heat;and the enhanced luminous eiciency of the glow discharge wills-largely,at least, make up for the relatively poor luminous eiileciency of suchafilament.

I also aim to provide a simple, compact, convenient lamp unit.- needingno extrinsic acces-v series such as external ballast, compensatingresistance,` reactor, ortransformer, and not even requiring the usualenclosing vacuum jacket; and to secure relativelyhigh over-all eilciencyof the whole unit. In a lamp unit of this character, I arrange forexternally heating the'glow discharge A lamp envelope or bulb walls asuniformly as possible all over, partly by arranging a plurality of ablyarranged to throw their heat on the un-4 blankete'd or outward-facingwalls of the closely grouped glow discharge lamp means. A particularlyfavorable combination is to alternate lamps or tubes and heating meansin a more or less regular, symmetrical arrangement with respect to acommon axis. I have here particularly illusandiilaments II, II arrangedin alternation, at`

trated and described my invention as applied to one or more glowdischarge lamps of cylindrical -.or tubular form enclosed with theexternal heating means in a cylindrical or tubular evacuated outerenvelope; but while the cylindrical or tubular shape lends itself veryadvantageously to my purpose, it is not essential. and the invention inits broader aspects can -be adapted to other shapes of glow dischargelamp and outer envelope. i

I aim, furthermore, to provide light of improved quality by combiningdifferent light color tones (produced either in the. same glow'discharge lamp, or in separate glow discharge lamps) with two or moredifferent ones of such working substances as sodium; potassium: or otheralkali metal, mercury, cadmium, calcium. or magnesium,'etc.; also bycombining the light of solid filaments or glow bodieswith glow dischargevapor lamp light. I Either or both of these measures may be employed inlighting units such as referred to in thepreceding paragraph. A

Various other features and advantages of the invention will appear fromthe following description of species thereof, and from the drawings.

In the drawings, Fig. l is a side view of one form of lamp unitembodying my invention; Fig. 2 is a view of the mount of the unit shownin Fig. l at right angles to Fig. 1, without the outer .enclosingenvelope or the contact terminals of Fig. 1; Fig. 3 is a somewhatdiagrammatic plan view of the mount; Fig. 4 is a view similar to Fig. 1illustrating a lainp unit of somewhat different construction, with anelectrode of one of its glow discharge lamps in axial vertical sec--vention; Fig. 10 is a schematic wiring diagram.

of the embodiment of the invention illustrated in Figs. 1 to 3 and theembodiment of the invention illustrated in Figs. 4 to 6 and Fig. 11 isa' schematic wiring diagram ofthe embodiment of the'inventionillustrated in Figs. 'I and 8 and the embodiment of the inventionillustrated inFlg. 9.

4 The device shown in Figs. 1-3 comprises elongated, tubularv glowdischarge vapor lamps I0, I

substantially uniform intervals, and in symmetry with respect .to acommon axis or center. This gives a substantially uniform distributionof light and heat. As only two lamp tubes I0, I 0 and two filaments II,II are usedvin this particuiar' device, the arrangement is a quadratedgaps) and iilaments II, II extend in the same general direction,substantially or approximately paral1el.- Lamps I0 and filaments II areall enclosed in an evacuated and sealed (glass) envelope or bulb I2, oftubular form, which not only protects the filaments Afrom theatmospheric oxygen, but also minimizes radiation and loss of heat fromthe lamps, as well as from the iilaments. rlfhe laments II, II arepreferably of tungsten,

vor other material having a positive temperatureresistance coeilicient.

In the present instance, the device is shown equipped with a` unitarybase and contact terminal structure I3 which in effect forms part of theouter envelope I2 itself, rather than with a separate base secured to anenvelope complete in itself, apart from the basel This structurencomprises a cup-like body I 4 of glass with downward projecting hollownipples I5, I5 to which are fused hollow metal terminal posts orthimblesleeves IG, I6 closed at their lower ends. Such a unitary contactterminal structure is commonly known in the artas a bi-post base. Metalcurrent leads I1,4 I1, preferably of channel section, are attached tothe hollow contact terminals I8, IB inside the latter, and extend upthrough the nipples I5, I5 into the cup-like body Il. 'I'here theseleads I1, I1 are offset (by double bends) toward the center of.` theenvelope I2, so as to extend 4inward close beside-one anothersubstantially or approximately along the center or axis of the envelopeand of the assemblage of lamps III, III and filaments II, II.v In otherwords, the lamps and filaments are arranged in a hollow coniigurationaround the current leads I1, I1. The exhaust tip I 8' on the glass bodyI4 is also shown sealed oiI. t A

The lamps' III, I 0 are supported at their lower ends by or from thestructure I8, and at their upper ends by or from the upper or inner endsof the leads'I1, I1. As here shown, each lamp II) comprises as itsenvelope a glass tube with annularly shouldered or ridged metal contact.discs I8, I8, fused to its ends. In the particular construction lhereillustrated, the lower ends of the lamps Ill, III rest against aninsulating bar or block 20 that extends diametrallyacross the interiorof the cup-like body Il, this block 20 being notched at 2|, 2| toreceive the ridge of each lower disc. I8 and aiord a button" to engageinside this annular ridge. The upper end of each lamp II) vis held by aflexible wire spring nnger 22 that has one end fastened to the upper endof one of the leads I1, and has la circular loop 23 on its free end toengage around the annular ridge of the corresponding disc I8. Eachspring finger 22 electrically connects its lead I1 to ,the upper contactI8 of its lamp I Il, and presses the ridge of the lower contact I8against a sheet metal contact strip 2l that extends .into one of prisestwo separate wire sections which carryglass insulating beads 28, 21 andhave their adjacent ends fused into a glass insulating and connectingbead 28. Lower and upper support arms 30, 3I are welded to thecorresponding insulatively separatedupper and lower sections of theupright 25 and to the ends ofthe filament II, and serve as currentconnections for the filament Il. Intermediate support arms 32, 32 arefused into the glass beads 26, 21, 28 to serve as anchors. Each upright25 is insulatively supported from the corresponding main current lead I1by composite insulating arms 33, 33, whose wire sections are fused intoglass insulating beads.

' To ballast the lamps I8, I8, each of them is connected in series withone of the filaments II, II. While the resultant lamp-and-filament setsmay be cnnected'in parallel between the leads I1, I1, in the presentinstance I have shown them,

in series with one another between said leads, so that the device can beoperated on standard lighting circuits of around 110 to 120 voltswithout being excessively large, or requiring excessively fine filamentsII, II. For this purpose,

the upper sections of the uprights 25, 25 arev interconnected by a wire35 extending across the upper end of the bulb I2, above or between thengers 22, 22-indeed, this Wire 35 and the sections of the uprights 25,25 which itconnects may consist of one single length of wire bent to aninverted U shape, as here shownand the lower ends of the lower sectionsof the uprights 25, 25 are connected by wires 36, 36 to the contactstrips 24, 24. Thus the filaments II, II are connected in series betweenthe lower ends of the lamps I8, I8, whose upper ends are connected tothe leads I1, I1 as already described.

Recurring to Fig. 1, and referring to the internal features or mounts ofthe lamps I8, I8, it will be seen that each lamp`has in the oppositeends of its tubular envelope the electrodes 48, 48, preferably ofindirectly heated type such as known in the art. These electrodes 48, 48are supported by an upright 4I comprising a main wire section and lowerand upper Wire L parts 42,43 attached to .said main section byinsulating glass beads 44, 44 into which the parts are fused. From themain wire section project wire arms 45, 45 Welded thereto, parallel withthe arms of the parts 42, 43 and spaced from them about the length ofthe electrodes 48, 48. One electrode 48-or, more properly speaking,itsvinternal heating resistance 46-is connected between the lower arms.42 and 45, and the other between the upper arms 43 and 45. Aninsulating refractory sleeve 41 (or a glass tube) surrounds the mainsection of upright 4I between the arms 45, 45. The lower arm 42 haswelded thereto a wire support 48 that engages the' lower disc I8 andelectrically connects the arm thereto, and the upper arm 43 has aflexible electrical connection 49 to the upper disc I8. Thus theinternal heating resstances 46, 46 of the electrodes 48, 48 areelectrically connected in series between the lower and upper discs I8,I8.

To the insulating sleeve or tube 41 of each glow discharge lamp I8 isattached a hermetic capsule 58 containing a charge of sodium or othersuch vaporizable Working substance for the lamp. This capsule 58 may beof glass hermetically sealed, and may be encased in a piece ofthinwalled nickel tubing 5I crimped in at the ends to retain thecapsule. The capsule 58 is thus installed on the mount of the lamp lobefore, the vmount is sealed into its tubular envelope. After thevlamp-I8 has been exhausted-and preferably quency coil is powerfulenough, the metal casing 5I may be dispensed with;-although it is usefulto retain the pieces of the ruptured capsule. If preferred, therupturing of the capsule 58 may be done after the lamps I8, I8 have beeninstalled in the outer envelope I2, and the latter exhausted and sealedoff.

Besides the charge of sodium or the like, each lamp I8 preferablycontains a tenuous atmosphere of neon, argon, or other suitable gas thatis readily ionized. This is introduced after the lamp I8 isexhausted,'but before it is sealed oi.

In the operation of the device, starting cold, the currentiiows at rstthrough the electrodeheating resistances 46, 46 and the main section ofthe upright 4I of each lamp I8, in series; but as the electrodes 48, 48heat up, more and more current is carried by ions of the neon or othergas in the gap between them. As the whole lamp `I8 heats up andvaporizes some sodium or other metal, the metal ions participate in theluminous discharge, in shunt with the resistances46, 46 and upright 4I.Besides being internally heated by its electrode-heaters 46, 46, and,its glow discharge, each lamp I8 is externally heated by the adjacentlamp and by the laments II, I I, whose 4arrangement with reference tothe lamps I8, I8 and the envelope I2 assures a very uniform distributionof this external heatto the lamp'tube walls; since the heat of thefilaments striking the walls of the outer envelope I2 obliquely isreflected and reradiated back on `those portions of the lamp tube wallsthat receive theA least -heat directly. Thus the distribution of heatthroughout the evacuated outer envelope I2 is very uniform.

. The vacuum in the envelope I2 minimizes loss of heat by conduction orconvection. The efhcient external heating of the lamps I8, I8 by thefilaments I I, II helps to .vaporize the sodium or other glow dischargeeiciency than if the lamp itself had to be forced in order to vaporizemore sodium by the heat of the glow`discharge;and thus the filaments II,II, though themselves generallynferior in luminous emciency to the lampsI8, I8, nevertheless very greatly increase the overall efclency of thewhole device. Such a lamp may be operated at aboutu250 C. with a lglowdischarge energy consumption as low as about 0.1 watt per squarecentimeter of envelope surface. The filaments II, II ballast the lamp I8., I8 very satisfactorily, as already explained.

'I'he combination of'the light II of tungsten with the lyellow lightfrom sodium pf filaments A'I I, v65

vapor gives a combined light o f improved quality. By using one lamp I8with sodium and anafter it has been sealed off-the metal-cased cap-\'\yellow sodium and the blue-green mercury lighttones with the(yellowish) white of tungsten.

suie 58 is brought into the fleldof a high frequency coil externallysurrounding the lamp I8.

Alsotwo or more working substances may be two lamps I and more than twotungsten or other filaments II can be used in an arrangement similar tothat of Figs. 1 3; with different substances in the respective lamps,such as sodium, mercury, and cadmium.y More vcomplete mixture of thediierent kinds or color-tones of light can be obtained by enclosing thedevice in a light-diffusing globe, or by frosting the envelope I2, or bya combination of such measures.

In Figs. 4-6, the arrangement of the tubular lamps Illa, Illa andlaments I I, I I is similar to that shown in Figs. 1-3, but the mountingis different, as well asl the construction of the lamps. In thisinstance, lamps Illa, Illa and laments I I, II are all supportedentirely from the main terminal post leads I1, I 1. 'I'he iilaments II,I I are not coextensive with thelamps I0a, Illa throughout their fulllengths, as in Figs. l and 2, but only with the'gaps between theirelectrodes 40a, 40a, or nearly so. Each lamp Illa has an all-glass'envelope with current leads 53, 53 centrally sealed through itsopposite ends andconnected to the axially arranged glow-dischargeelectrodes 40a,

40a, which-or their internal heating resistances 46a, 46a-areinterconnected' by an axially ex-` tending (molybdenum) lead 4Ia, theupright 25 and associated parts of Figs. 1-3 being dispensed with. Theseelectrodes 40a, 46a, are of internally emissive hollow type: i. e., eachof them has -its electron-emissive material (such Kas barium oxide) onthe inner surface of a (nickel) metal tube that is open toward the otherelectrode.

The lamps Illa, Illa are supported at their upper ends by or from theinner ends of the leads I1, I1, which extend side by side very much asin Figs. 1-3, but in the plane of the terminal posts I6, I6 instead ofin a plane at right angles thereto. The leads I1, I1 are insulativelyinterconnected and spaced apartby braces 54, 54 welded tothe leads near`their lower and upper ends, each brace comprising wire-sections fused vinto an insulative (glass) piece. Each lamp has its upper lead 53attached and electrically connected to the horizontal arm of an(inverted) L-bent wirev lead support 55 whose upright member is fastenedto the end of its (channel) lead I1. An insulative (L-bent) brace 56comprising wire sections fused into a (glass) insulating piece has oneend welded to the outer end of a lead 53 and its other end fastened tothe en'd of a (channel) lead` I1. At the lower ends of the lamps I0a,IIIa, there are two U or J-bent lead wires 51, 51, whose short limbs arewelded -to the lower lamp leads 53, 53, and whose long limbs extendupward in the plane of the laments I I, II, at right angles to that ofthe-lamp tube axes, and mid? way between them. For the short limb ofeach J 51, there are insulative braces 58, 58 (similar to the braces 54and 56 in construction), extending from a common point on the J-limb tothe two nleads I1, I1. The lower end of each filament II is(electrically) connected to the upstanding long limb of a J 51, and itsupper end is connected to the depending limb of an (inverted) U-bentlead wire 35 that extends horizontally across between the upper ends ofthe lamps I0a, I0a. The horizontal' member 'of the U-bent lead wire 35is shown in Fig. 5 as oiset to one side of the plane of the filamentsIl, II, to keep it clear of the leads I1, I1. The upstandinglong limb ofeach lament II may have an insulative anchor support'GI, (similar to thebraces 54, 56, 58, 60 in construction) welded to the adjacent lead I1and embracing the filament about at mid-length.

Thus, it will be seen, the iilaments II, II are connected in series withone another by the wire 35, and the serially connected pair of them isconnected in series between the lamps I Ila, IUa by the wires 51, 51.And the serial chain of lamp I0a,laments II, II, and lamp I 0a isconnected in series. between the terminal leads l1, I1 by the lamp leads53, 53.

In the device shown in Figs. 'l and 8, the two lamp tubes Ib, Illbcorresponding to the separate lamps I II, Ill of Figs. 1-3 and 4-6 arelimbs of a single (inverted) U-tube lamp, but are still arrangedsymmetrically and in alternation with the iilaments II, II, as in Figs.1-6. The U-Iamp limbs I0b, IIlb are supported entirely from the base andterminal structure I 3, by means of separate saddle devices 20a, 20a,each consisting of a. glass flare fused to the upper end of a metal tolie against the inner wall of the U-bend of the lamp I 0b. The(g1ass).ends of the lamp IIIb may be fused to the (glass) flares of thesaddle devices 20a, 2Ilaj The ilaments I I, II are only coextensive withthe U-bent electrode gap, or approximately so. They are supported andIinterconnected at their upper ends by a (nickel) lead wire 25h coiledaround the bend of the U-lamp IUb about 11/2 turns, with its endportions at opposite sides of the exhaust tip 14 on of the saddlesleeves 10, 10, and extend upward beside one another neari-the axis ofthe envelope, etc'., like the leads 24, 24 in Figs. 1-3 and 4 6. 'Ihesupport 24a forms a current lead connecting -its filament- IIl directlyto the left-hand saddle sleeve 10 and terminal I6. The other support24h, attached to the right-hand saddle sleeve 1P, comprises two sectionsmechanically connected but insulated from one another by a (glass)insulating piece 15, thus insulating the main section of this supportfrom said sleeve 10. 'Ihe left-hand electrode lead 13 extends downthrough the corresponding sleeve 10, out through a hble in the sleevewall in which itis insulatively sealed at 1 1, and then to the mainsection of the lead 24h, to which it is welded at 18. The righthandelectrode-lead 13 extends down in the corresponding sleeve 10 and iswelded thereto at 15. Thus the filaments lI I, I I are connected inseries with one another and with the electrode gap 4I), 40 of theU-.lamp. e

In manufacture. `the U-lamp Illb with its internal parts is completedand exhausted, charged with neon or other gas and sodium or otherworking substance, and sealed oif at 15. Thenthe saddle devices 20a,20a., are attached and the lead coil 25h put in place. 'I'he filamentsII, III are installed and the. electrode leads 13, 13 are arranged asdescribed above and connected, one to the support 24h and the other tothe right hand saddle sleeve 10.- 'I'he supports 24a, 24h may be weldedto the sleeves 10, 10 either before or after attaching the .saddles 28a,20a to the lamp. The lamp and filament assembly is now mounted on thebase I3 by inserting and securing the saddle sleeves 10, 10 in the baseterminals I6, I8. The mount thus completed, it is inserted in the outerbulb I2 and sealed in, and the outer bulb is exhausted and sealed oi atI8'. Holes 80, 80 in the sleeves 10, 10 allow their interiors to beexhausted.

Fig. 9 shows a U-lamp Ib like that of Figs. '7 and 8, supported entirelyfrom' the base I8 by a unitary saddle structure 25e, consisting of an(inverted) glass body resembling the body Ill of the base I3, butwithout the attached terminals I8, I8. The ends of the U-lamp limbsi012, Ib are fused to the upper ends of the nipples I5, I5; but theexhaust tip I8 is left open toA allow of exhausting the outer bulb I2through the base tip I 8 as usual. The lower filament lead supports 24e,24e are fused through the bottom of the saddle body 25e, Within or belowthe saddle 25e, one support 24o is electrically connected to an offsetterminal lead I 1c (resembling one of the leads I1 in Figs. 1-3) by aspringy helically wound lead wire 82, while the other support 24e hasthe (left-hand) electrode lead 13 weldedto it.`

II, II are all installed on the saddle 25e, andA their connectionscompleted as far as possible.v

This lamp and filament assembly is then placed over the base I3 and theleads 82 and 13 are ut to length and temporarily pinched to the leadsI1c, I1c. Then saddle 25e is separated from base I3 slightly-helicallead portions 82 and 83 stretching to permit this-and the lead 82 iswelded to its terminal lead I1c, and the (right- 4 hand) lamp electrodelead '13 is Welded to the otherlead I1c. Then theV saddle 25e is broughtdown against the base body IQ-the helical lead portions 82 and 83contracting to obviate any slack-and fused thereto around its periphery.

Themount, thus completed, is inserted in the outer bulb I2 and sealedin, and the latter is then exhausted at I8 and sealed off.

What I claim as new 'and desire to secure by Letters Patent of theUnited States is:

1. A lamp unit comprising a pluralityof glow discharge vapor lamp tubemeans close alongy elements coacting with the heat of the lamp tubemeans and with said outer envelope to heat the lamp tube meanssubstantially uniformly to a temperature sufficient to maintain thereinan adequate atmosphere of vaporous working substance with a low glowdischarge current density..

2. A lamp unit comprising a plurality of glow discharge vapor lamp tubesclose `alongside one another, thus blanketing one anothers heat;-

incandescent filament lengths extending alongside the adjacentunblanketed sides of said lamp tubes, said lamps and said filamentsbeing mounted about and at equal distances from a common centerand inevenly spaced alternate positions about said center; and an evacuatedenvelope containing said lamp tubes and filament lengths and reflectingand reradiating the filament heat back on the outward-facing tube walls,so as to coact with the heat of the lamp tubes inv heating the tubewalls vsubstantially uniformly to a temperature sufficient to maintaintherein an adequate atmosphere of vaporous working substance with a -lowglow discharge current density.

3. A lamp unit comprising a group of substantially parallel glowdischarge vapor lamp tubes; a plurality of incandescent filament lengthsconnected in series with said lamp tubes as ballast and arranged in`alternation with said lamp tubes at equal distances therefrom and from acommon center and substantially parallel with 4. A lamp unit comprisinga pair of glow dis-` charge vapor lamp tubes close alongside one an.-

other, thus blanketing one anothers heat; a pair of incandescent lamentlengths extending alongsidev said pair of lamp tubes at opposite sidesthereof, outside the space between them and at equal distances from acommon center; and an evacuated envelope containing saidv lamp tubes andfilament lengths in its vacuum space.

5. A lamp unit comprising a plurality of glow discharge vapor lampscontaining different working substances which are vaporous in theoperation of the lamps and give luminous glow-discharges of differentcolor tones; a plurality of incandescent filament lengths connected inseries with said lampsV to ballast them and arranged in oalternation'with the lamps and substantially parallel in direction withtheir discharge gaps; and

an evacuated envelope enclosing said lamps and filament lengths in itsvacuum space, said lamps and said filaments being at equal distancesfrom a common center. 6. A lamp unit comprising a plurality of glowdischarge vapor lamps and a plurality of incandescent filaments allconnected in series with one another so that the filaments-ballast thelamps and-so that the combination can operate on ordinary standardlighting voltages; the filaments being arranged in alternation with thelamps about and at equal distances from a common, center and beingsubstantially parallel in direction with their discharge gaps, and anevacuated envelope enclosing said filaments and lamps in its vacuumspace.

7. A lamp unit comprising an outer evacuated envelope provided withcontact terminals at` one end; current leads connected to said ter-`minals and extending inward ,close beside one another, substantiallyalong the `center of the envelope; a 'plurality of tubular glowdischarge vapor` lamp tubes in said envelope arranged around saidcurrent leads, substantially parallel with them, and supported from themand electrically connectedto" them at their own inner ends; and aplurality of incandescent lament lengths extending parallel with saidlamps in f base and terminal structure; current leads attached to theterminals of said structure and extending therefrom side by side; aplurality of glow discharge vapor tubes extending substantially paralleland supported from the inner ends of said current leads and`electrically connected thereto at their own inner ends, and sup` portedat their other ends from said unitary structure; and a plurality ofincandescent Illa--` ment lengths having positive temperature resistancecoeilicients extending parallel withv said lamps and electricallyconnected in series with the lamps to' ballast them, said lamps and saidlaments being in evenly spaced alternate positions about a commoncenter.

9. A lamp unit mount' comprising a unitary base and terminal structure,saddle means mounted thereon, glow discharge vapor lamp means mounted onsaid saddle means, illament supports and current leads also mounted onsaid saddle means, and incandescent filament lengths attached andelectrically connected to said ilia-` ment supports and current leads,said vapor lamp means and said 'illament lengths being mounted inalternate positions about a common center. y

l0. A lamp and lament assembly comprising a glass saddle structurepresenting seats ffor glow discharge vapor lamp tube ends, a glow'discharge vapor lamp tube with its ends mounted on said seats, illamentsupports and current incandescent ilament lengths attached andelectrically connected to said illament supports and current leads, saidlamp tube and said nlament lengths being mounted in` alternaterpositions about a common center.

11, 'I'he combination witha unitary base and terminal structure having ahollowr projecting terminal post, of a glow dischargeavapor lamp,

and a saddle attached to the end of said lamp and comprising a metalsupport member engaged in said. hollow terminalpost of said base andterminal structure, and electricallyconnected 'to an electrode of saidglow discharge vapor lamp.

l2. The combination with a unitary base and terminal structure having ahollow projecting terminal post, oi a saddle comprising a hollow metalsupport memberA engaged inv said hollow terminal post, and a glowdischarge vapor lampl attached.- to said saddle having a current leadextending through said hollow metal member and electrically connected.thereto substantially at its end in said terminal post.

13. A lamp unit comprising an evacuated bulb|` mounted `in said bulbwith its leg ends attached to the based end thereof; a current leadattached lamp having its ends attached to said saddle`- 40 means,filament supports and current leads mounted on said saddle means and onthe U- tube bend, and incandescent laments attached 'and electricallyconnected to said filament supports and current leads, the legs or saidlamp and saidillaments being at equal distances from a common center.

GEORGE E. INMAN.

